The invention deals with an LED module which can be used, for example, in retrofit LED lamps which are designed as a replacement for halogen lamps or incandescent lamps.
LED lamps are being used more and more often for illumination. Said lamps are distinguished by their high light efficiency and their longevity. Furthermore, said lamps can be used in a very flexible manner on account of their extremely small dimensions. LEDs are mostly produced in the form of LED modules. In this case, LED modules consisting of at least one blue LED which produces white light by means of wavelength conversion means arranged on the LED should be considered. RGB LED modules can be used to produce any desired colours, in which case a setting process and a dimming process can be carried out by means of PWM driving of the individual colour channels.
LED lamps can be used in the form of so-called retrofit LED lamps. In this case, the LED lamp has the form and function of a conventional light bulb, for example, but comprises one or more LEDs or one or more LED modules as luminous means. In order to match the supply current, the retrofit LED lamp also has its own driver circuit which matches the supply current to the operating conditions of the LEDs on the basis of a mains voltage supplied via the cap, for example. The LED retrofit light bulbs can therefore be screwed into conventional lamp holders like conventional light bulbs and can be operated using the mains current supplied.
However, in the case of LED modules which integrate LED chips on a common carrier, the problem arises of the emitted light from the at least two (or more) LED chips with different emission spectra having to be mixed as homogeneously as possible in order to produce white light with an adjustable colour temperature.
The known optical elements which are used to mix light are diffusers, lenses, reflectors etc. and the combinations thereof.
However, the use of a diffuser, for example, as an upper part of an LED lamp with the proposed solution results in the problem of negative shading effects being able to arise in an edge region of the upper part in the form of the diffuser. In other words, if this edge region of the upper part in the form of the diffuser is viewed with the human eye, the situation may disadvantageously occur in which locally separate spectra or colours can be seen, as a type of backlit lampshade, rather than the mixed spectrum of the at least two LED chips.